1. Field of the Invention
The present invention relates to a drip absorption mat laid under foods such as meat and fish which are apt to ooze drips, and more specifically to a drip absorption mat which prevents foods from color deterioration in contact with the drip absorption mat.
2. Description of Related Art
In food counters in supermarkets or the like, foods such as meat and fish in a fixed amount are separately placed in a tray, packed in a transparent wrapping film, and displayed for sale. Under such sale's conditions, foods are often left on the display shelf for a long time so that drips are apt to accumulate in the tray. It is not only spoiling the appearance of foods but also causing tire accelerated deterioration thereof. Therefore, in the tray on which drip-oozing foods such as meat and fish are placed is usually underlied a tray mat to absorb drips.
Appropriately cut non-woven fabric may be used as such a type of tray mat. However, in a tray mat comprising only a single layer of non-woven fabric, absorbed drips can be totally seen from the tray mat surface, spoiling the appearance of foods. In addition, since drips absorbed are in a state wherein they are directly in contact with foods, a tray mat of this type is not so effective in retarding the food deterioration.
Therefore, to solve these problems, there has been proposed a type of tray mat comprising a non-woven fabric with a film having apertures pasted thereon. Tray mate of such type have been disclosed, for example, in Japanese Utility Model Application Laid-open No. Hei 3-85886 and Japanese Patent Application Laid-open No. Hei 9-86569. In such a tray mat, an opaque porous plastic sheet provided with numerous three-dimensional apertures is pasted on the surface of a liquid absorptive absorption sheet. According to the tray mat disclosed in these official gazettes, as the surface of absorption sheet is covered with a sheet provided with numerous apertures, drips absorbed into the absorption sheet are separated from foods so as not to be left also on the surface of tray mat. Accordingly, foods placed on the tray look good, and are protected from the progressive deterioration caused by drips.
However, in a tray mat described in the aforementioned official gazettes, the color deterioration of foods in contact with the mat has not been much taken into consideration. In the case where such a tray mat is used, there has been raised new problem that food browning (color deterioration of food) is in progress at the portion in contact with the tray mat (that is, the rear portion of foods). Even though the food browning occurs on the side invisible from outside, it results in giving consumers who have bought that food an unfavorable impression on the quality of said food.
In this regard, according to the research by the present inventors, the color change of foods is caused by the alteration of myoglobin contained meats, etc.
That is, the color of meat such a beef and fish meat such as tuna is altered depending on the type and ratio of myoglobin derivatives present therein. Herein, as types of myoglobin derivatives, there exist the reduced type myoglobin, oxymyoglobin and metmyoglobin. The reduced type myoglobin is purple red, oxymyoglobin is scarlet, and metmyoglobin is brown. Freshness impression is given to consumers in the decreasing order of scarlet>purple red>brown.
In this regard, the meat immediately after excision (cut in slices) contains almost nothing but the reduced type myoglobin, appearing purple red. When this meat is left in the atmosphere, the reduced type myoglobin is coordinated with an oxygen molecule to form oxymyoglobin so that the meat appears scarlet. When further left in the atmosphere, oyxmyoglobin is oxidized to form metmyoglobin, so that the meat turns to brown.
Herein, color deterioration of meats is caused by meat browning due to the formation of metmyoglobin as described above, which formation is accelerated by effects of oxygen partial pressure, temperature, humidity, pH, salt concentration, and light, etc.
However, present inventors' researches have revealed that, in comparison of the case where metmyoglobin is formed from the reduced type myoglobin via oxymyoglobin (reduced form myoglobin→oxymyoglobin→metmyoglobin) and the case where metmyoglobin is directly formed from the reduced type myoglobin not through oxymyoglobin (reduced form myoglobin→metmyoglobin), the former case retards the meat color deterioration due to the formation of metmyoglobin and that alteration process as in the former case can be secured by sufficient breathability provided in the drip absorption mat laid under meats.